重构if-else语句检查不同的文件扩展名

Question

我有一段我觉得可以清理的代码(我可能是错的)，但我想看看是否有人能给我一个建议，让它变得更“更好”。

string getExt = Path.GetExtension(DocumentUNCPath.Text);
        var convertFileId = Guid.NewGuid();
        var convertFilePath = @"c:\temp\" + convertFileId + ".pdf";


        if (getExt == ".doc" || getExt == ".docx" || getExt == ".txt" || getExt == ".rtf")
        {
            WordToPdf(convertFilePath);

        }
        else if (getExt == ".xlsx" || getExt == ".xls")
        {
            ExcelToPdf(convertFilePath);
        }
        else if (getExt == ".jpg" || getExt == ".png" || getExt == ".jpeg" || getExt == ".JPG" || getExt == ".PNG")
        {
            ImgToPDF(convertFilePath);
        }

Answer 1

以下代码最初可能更多，但可以更好地扩展。

在方法之外：

    public static readonly List<string> WorkExtensions = new List<string> { ".doc", ".docx", ".txt", ".trf" };
    public static readonly List<string> ExcelExtensions = new List<string> { ".xlsx", ".xls" };
    public static readonly List<string> ImageExtensions = new List<string> { ".jpg", ".png", ".jpeg" };

方法内部：

    string getExt = Path.GetExtension(DocumentUNCPath.Text);
    var convertFileId = Guid.NewGuid();
    var convertFilePath = @"c:\temp\" + convertFileId + ".pdf";

    getExt = getExt.ToLower();

    if (WorkExtensions.Contains(getExt))
    {
        WordToPdf(convertFilePath)
    }
    else if (ExcelExtensions.Contains(getExt))
    {
        ExcelToPdf(convertFilePath);
    }
    else if (ImageExtensions.Contains(getExt))
    {
        ImgToPdf(convertFilePath);
    }

Answer 2

将扩展映射到处理程序是处理此类情况的标准方法：

// populate with { ".doc", WordToPdf } and similar pairs
Dictionary<string, Action<string> > handlers = ... 


// find and call handler by extension 
// (use TryGetValue to check for existence if needed)
handlers[getExt]( convertFilePath );

Answer 3

你可以这样做

    switch (getExt.ToUpper()) 
    {    
       case "JPG":    
       case "PNG": 
....